Design a single-phase bipolar PWM inverter which will produce a 75V rms 50Hz from a 150V dc source. The load is a series combination of R=12 Ohms and L=60mH. Select a switching frequency such that the current THD is less than 10%. State assumptions used in the design.
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Help me solve this problem please..!!!
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Assume: You want sinusoidal waveform, capacitance is negligeable, Voltage switching instantaneous (rise time=0)
Calc. desired peak current -- from this max. duty cycle.
From time constant, calc. current waveform (exp. up/down)
as function of PWM frequency and its Fourier series.
THD as function of Fr --- solve it for <<10%
You may sum the infinite series or estimate the # of harmonics you have to use.
I suggest you to write a computer simulation for reality check -- it shoud'n take more than a few hours.
<nbucska@pcperipherals.com>
Calc. desired peak current -- from this max. duty cycle.
From time constant, calc. current waveform (exp. up/down)
as function of PWM frequency and its Fourier series.
THD as function of Fr --- solve it for <<10%
You may sum the infinite series or estimate the # of harmonics you have to use.
I suggest you to write a computer simulation for reality check -- it shoud'n take more than a few hours.
<nbucska@pcperipherals.com>
jbartos
Electrical
- Jan 15, 2000
- 6,440
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